Late-Stage Modification\nof Peptides with Maleimides\nthrough Palladium-Catalyzed β‑C(sp<sup>3</sup>)–H\nAlkylation

Transition-metal-catalyzed C–H activation has\nproven to\nbe a powerful tool for the late-stage modification of peptides. We\nherein report a method for site-selective alkylation of peptides with\nmaleimides through Pd-catalyzed β-C(sp<sup>3</sup>)–H\nactivation. In this protocol, the methionine residues within peptides\nserve as the directing groups, which circumvented the preinstallation\nand subsequent removal of the directing groups. This chemistry exhibited\nbroad substrate scope and can be utilized for peptide ligation.